Extensive studies have been carried out on radical polymerization in the past. Among them, in recent years, a living radical polymerization method has attracted attention, in which a polymer with a narrow molecular weight distribution is manufactured by arbitrarily and strictly controlling the molecular weight of the polymer obtained or a new polymer (block, graft, star or brush polymers, and the like) is manufactured by copolymerizing several monomers by various methods. Among them, Atom Transfer Radical Polymerization (ATRP) has been widely studied because it can precisely control the polymer structure in various forms. For example, Japanese Patent Laid-Open Publication No. H10-509475 (Patent Document 1) discloses a method for polymerizing a radically polymerizable monomer by using an organic halogen compound as an initiator, a transition metal halide such as copper halides and the like as a catalyst and further bipyridine and the like as a ligand for the transition metal compound. This method, however, uses expensive ligands and may require as much as threefold equivalents of the ligand with respect to the transition metal compound, causing a drawback of high cost in industrial production of the polymers.
On the other hand, Japanese Patent Laid-Open Publication No. 2002-540234 (Patent Document 2) discloses a living radical polymerization method to solve the above drawback. That is a method not to use expensive ligands. Specifically, it is a method to use an organic halogen compound as an initiator and a catalyst composition comprising an onium salt such as tetrabutylammonium bromide and the like and a transition metal halide such as an iron halide and the like, to polymerize a radically polymerizable monomer. This method does not require expensive ligands, but the reaction rate is low and cannot be considered as a favorable industrial process. Patent Document 2 also describes a need to add an expensive ligand (for example, N-(2-pyridylmethyl)methamine and the like) in order to increase the reaction rate.
Further, Japanese Patent Laid-Open Publication 2000-355606 (Patent Document 3) and International Publication No. WO02/30995 Pamphlet (Patent Document 4) disclose a method for manufacturing a polymer by anionic polymerization of a polar unsaturated compound in the presence of a phosphazenium compound, which is one of the component compounds in the polymerization catalyst composition of the present invention. There is, however, a drawback that anionic polymerization is generally susceptible to impurities such as moisture and the like. Accordingly, a catalyst and a polymerization method have not been found yet, which permits use of a radical polymerization method to allow the polymerization even in the presence of moisture and the like, but does not use an expensive ligand to effect the living radical polymerization at a high reaction rate.    Patent Document 1: Japanese Patent Laid-Open Publication No. H10-509475    Patent Document 2: Japanese Patent Laid-Open Publication No. 2002-540234    Patent Document 3: Japanese Patent Laid-Open Publication No. 2000-355606    Patent Document 4: International Publication No. WO02/30995 Pamphlet